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AT32F435/437
Series Reference Manual
2022.11.11
Page 628
Rev 2.03
unavailable) is set in the statue register. Transmission
command is valid only when the transmission is stopped.
If the transmit command were issued before setting the
transmit descriptor list address register, the DMA will show
unpredictable behavior.
When this bit is cleared, transmit process enters stop state
after the completion of a frame transmission. The next
descriptor position in the transmit list is saved, and
becomes the current position when transmission gets
started. To change the list address, write a new value to
the transmit descriptor list address register when this bit is
reset. The newly written value becomes effective only
when this bit is set again. The Stop Transmission
Command is effective only when the current frame
transmission is complete or transmit process enters
suspend state.
Bit 12: 8
Reserved
0x00
resd
Kept at its default value.
Bit 7
FEF
0x0
rw
Forward Error Frames
1: All frames except runt error frames are forwarded to the
DMA
0: Rx FIFO drops error frames (CRC error, collision error,
giant frame, watchdog timeout and overflow). However, if
the frame’s start byte point has already been transferred
to the application in Threshold mode, then the frames are
not dropped. The Rx FIFO drops the error frames whose
start bytes have not been transferred to the AHB bus.
Bit 6
FUGF
0x0
rw
Forward Undersized Good Frames
When this bit is set, the Rx FIFO forwards undersized
good frames including pad bytes and CRC (with no error
and length less than 64 bytes)
When this bit is cleared, the Rx FIFO drops all frames with
a length less than 64 bytes, unless such a frame has
already been transferred to the application due to a lower
value than the receive threshold (e.g. RTC=01).
Bit 5
Reserved
0x0
resd
Kept at its default value.
Bit 4: 3
RTC
0x0
rw
Receive Threshold Control
These two bits control the threshold of the Rx FIFO.
Transfer to DMA starts when the frame in the Rx FIFO is
larger than the threshold. In addition, full frames with a
length less than the threshold are also automatically
transferred.
Value 11 is not applicable if the Rx FIFO size is configured
to be 128 bytes.
These bits are applicable only when the RSF bit equals 0.
These bits are ignored when the RSF bit is set.
00: 64
01: 32
10: 96
11: 128
Bit 2
OSF
0x0
rw
Operate on Second Frame
When this bit is set, it instructs the DMA to process a
second frame of transmit data even before the status of
the first frame is obtained.
Bit 1
SSR
0x0
rw
Start or Stop Receive
When this bit is set, the receive process is in the running
state, and the DMA attempts to acquire the descriptor from
the receive list and processes incoming frames. The DMA
acquires the descriptor either from the current position in
the list (the receive list base address set by the receive
descriptor list address register) or from the position where
the receive process was stopped previously. If the current
descriptor is owned by the DMA, the receive process
enters suspend state, and the bit 7 (receive buffer
unavailable) is set in the statue register. Reception
command is valid only when the reception is stopped. If